The present invention relates generally to methods and apparatus for processing coils of metallic strip material, such as steel strip, and more particularly to a method and apparatus for removing irregular lap formations in such a coil.
In a coil of strip material, the strip is wound in laps of progressively increasing diameter. Each lap has two edges, one on each side of the coil. In a coil with regular lap formations, the edge on a given side of a lap is aligned with the corresponding edges of the same side of the other laps, and the coil side is flat. In a coil having irregular lap formations, the edges of at least some laps extend outwardly, in an axial direction of the coil a distance different than other lap edges on the same side of the coil. An irregular lap formation in a coil may manifest itself as telescoping laps, undulating laps or staggered laps, for example.
Many users of coiled metallic strip material cannot use coils having irregular lap formations. This is because the equipment they use to unwind and otherwise process the coils are not intended to operate on coils having irregular lap formations, and the strip in such coils will be damaged at the edges when processed by this equipment. This problem is virtually nonexistent for coils with regular lap formations.
In the past, when the problem of irregular lap formations arose, the entire coil was unwound and then rewound with particular care to assure that the rewound coil had regular lap formations. This was a difficult and time-consuming process. Moreover, when the metallic strip material was thick, e.g., 1/2 inch thick steel strip or the like, unwinding and rewinding was not practicable because the material was too heavy. When originally wound, this material was still hot, and thus it was much easier to coil than when cold.
Another disadvantage to coils having irregular lap formations is that the lap edges are much more readily damaged during transportation and handling than coils with regular lap formations.